Drilling control



Dec. 25, 1962 Filed June 27, 1960 W. B. BUFFINGTON DRILLING CONTROL 2 She ets-Sheet 1 INVENTOR IV/LUAM 8. Burn/van ATTORNEY Dec. 25, 1962 w. B. BUFFl NGTON DRILLING CONTROL 2 Sheets-Sheet 2 Filed June 2'7, 1960 INVENTOR v Mil/nun .6. BuFH/mra/v l i ATTORNEY 3,070,356 Patented Dec. 25, 1962 i 2; right toward the left at the hoist drum assembly in 3,070,356 FIG. 1; DLING CQNTROL FIG. 3 is a schematic circuit diagram illustrating the William .Bufiingkm, Odessa amgnm electrical control circuit of the present invention;

master Gil Tools, Inc., Odessa, Tex., a corporatron of 5 FIG. 4 is an enlarged plan View looking down upon a Texas Pi] d J 27 1960 N 38 823 speed governor having a drive wheel operatively engage g i ing a flange of the hoist drum;

FIG. 5 is a side elevation of the governor illustrated My invention relates to automatic control systems for in FIG. 4; and rotary well drilling rigs, and more particularly relates FIG. 6 is a front View of a pressure gauge used in the to improved automatic means for controlling to preadsystem with part of the housing thereof broken away to justed values the weight on a drilling bit and the maxishow the internal details thereof. mum rate of descent thereof. Referring now to the drawings, FIG. 1 shows a partial In the drilling and coring of wells wit-h rotary drill- View of a drilling rig comprising a derrick D, the upper ing equipment one of the most important factors influenc- POIUOI'I of which has been omitted, and this derrick having the rate of penetration of the bit and the straightness g a hoi P y shown) at its P Over Whlch of the hole drill is the amount of weight on the drilling a hoist line 1 is passed in a manner well known in the bit I t d illi i th Weight i t ll d b prior art, the hoist line engaging a block 2 which is atthe hoisting-drum brake serving to control the rate at tached t0 the E P end of a rectangular drill Stem 3 which the hoisting line which supports part of the weight passing through the rotary derrick table 4 and supportof the drill stem and bit is payed out for the purpose ing further a drill stem at its lower end (this drill stem of advancing the latter into the strata being drilled. The a t not being illustrated). The hoist line 1 has its amount f Weight on th hoisting li i shown b a dead end 1a anchored, as to a ring lb, and extends from Weight indicator, and in the simplest types of drilling its dead end over the pulley (not shown) located at the systems, the operator stands with his hand on the brak top of the derrick D and down in two runs is and 1d lever and manually releases the brake in small incre- Which pp the block and finally the line eXtends ments to maintain approximately the correct weight on over -P y at t 0f the derrick t a portion 16 the drilling bit. Other systems have been known in the 0f the 11116 Whlch 1s pp around the hoist drum 5 prior n; hi h Serve th purpose f t lli th of the drawworks. Thus, when the portion 1e of the waight on the drill bit by providing automatic control hOlSt line 1 i8 WOlllld 011 the drum 5 as it rotates clockof the brake on the hoist drum. These prior art sys- Wise in the block 2 i raised. terns, however, are more complicated and cumbersome The drum 5 has tWO flanges on Opposite sides thereof, than the present system and include a plurality of disadand at 1621st one Of thsss flanges y s as a ra Survantages which the present invention seeks to overcome. face aPted W y brake shoe 5 strat d Schemati- It is a principal object of the invention to provide cally in 1 as bslhg mounted an arm Pivotally an improved system for controlling the drawworks on a suppohtbd'oh the fhhW-Works frame 8 as at rightd ilh i hi h System i id bl i l d hand portion of the brake arm 7 is located outside of the therefore more economical and dependable than the frame 3 and has a Welght W attached thereto which is prior t systems of hi h 1 am aware, suflicient to apply the brake shoe 6 to the drum 5 and A further principal object of the invention is to pro- 40 Stop its rotation. This mechanism is illustrated only vide an improved hoist control system in which the rate schemfltlcahy h of descent of the drill is controlled to keep the weight I The tenslon the holst hhe 1 13 Same throughout on the drill bit substantially constant despite variations its length, 15 Well known, and thsfefOIe the Weight in the hardness of those strata which present substantial supported y the block 2 can be determined y detel resistance to the bit. However, when the resistance to mining the tension in the st i at its dead end 1a. penetration drops to a very low value, or to zero, then this P p a standard hydraulic Weight indicator the rate of descent is automatically limited to an ad. 13 16 attached to thd dead-end portion 1a Of [the hOlSt line justable maximum rate which is slow enough to prevent 1, Weight indicator also including a gauge 11 calijarring or damage to the drill assembly when reaching brated in terms of Weight Supported y the block 111 a solid stratum after breaking through a subterranean the cohventibhal type of hydTallhc indicator illustrated, void. the transmitting unit comprises a diaphragm 10a having Another major object of the invention is to provide a small block i P s against the twist line 1a S0 hoist control system which can be easily adjusted to mainas to form? h h f The diallhraglh 10a ehclosqs tain a preselected weight onthe drill bit or to limit the an y h s h Withlh h transnwtt r unit 10 and this rate of penetration and descent of the bit to a predeterhydrauhc fluld 1s Connected y tubing 100 With gauge i d maximum l 1-1 which is conveniently mounted :on a supporting post Still another major object of the invention is to pro- The g g 11 comprises a Bourdon type tube 11b vide a simplified fail-safe system in which the descent of w i can 3 6 F which Is anchored at the drill is advanced incrementally, but is automatically f end a ngld Supportmg block f- The h stopped if a failure of electric power should occur in 11b 18 ixmnected through the p with the tubmg the control systeln 10c which leads to the transmitting unit as stated above. Other objects and advantages of the present invention The nghft end of the.Bourdon tube .1117 1S conmoted will become apparent during the following discussion througila lmkage. 114W1th.an mm 12 pwotany Supported of the drawings wherein: on a pin 12a WhlCh also pivotally supports an ad ustable v member lie of the assembly. The linkage 11d rocks the 1 a islde of the Lower Pomon of f g arm 12 so that the teeth 12b on the toothed segment of mg mclufhng a demc]? upper f of wtflch f the arm 12 are rotated back and forth for the purpose been omitted because it 1s of conventional design, this of rotating a Spur 13 which is pivotany supported figure showlhg y ahtbmatlc control y m P in the meter housing and carries at its outer end a pointer tit/61y associated With the dFaWWOYkS of the g; 13a which cooperates with a scale 13b on the face of the FIG. 2 is an elevation view of the drawworks including the hoist and supporting frame looking from the gauge assembly 11. The member 11c within the gauge assembly 1'1 also supports a stationary electrical contact 14 to which a wire 14a is connected, which wire extends from the gauge assembly 11 together with a second wire 15a which is connected with a movable contact 15 carried on the lower end of the arm 12. The circuits to which the wires 14a and 15a are connected are shown in FIG. 3, which will be described in greater detail hereinafter. The support member 11c comprises an arm which is pivotally supported at its upper end on the pivot pin 12:: supported in the gauge housing, and the lower end of the arm He is normally urged to the left by the spring 16. A lead screw 17 having a knurled knob 17a is supported in a rigidly mounted block 18 which is internally threaded (not shown) so that when the lead screw 17 is rotated therein, the right end of the lead screw as viewed in FIG. 6 translates back and forth. The right end of the screw 17 engages a small block 19 which in turn engages the arm 112 at a slot 11 so that when the arm He is rocked back and fonth the small block 19 can translate in the slot 11 The block 19 has an upstanding flange 19a having a hole therethrough to receive the thinner stem portion 17b of the lead screw 17 which portion 17b passes through the flange 19a to provide lost-motion engagement therebetween. A stop 17c is provided at the outer end of the thinner portion 17b so as to prevent disengagement of the flange 19 with the thinner portion 17b. Ordinarily, the spring 16 pulls the flange 19a against the end of the lead screw and all (the way to the left on the thinner portion 1712, but the arm He can be moved counterclockwise against the bias of the spring 16 by counterclockwise movement of the arm 12.

From the above description, it should be apparent that the changes in pressure caused by movements of the diaphragm b in the transmitting unit 10 of the weight indicator cause the right end of the Bourdon tube 11b to move back and fonth so as to rotate the arm 12 around the pivot pin 12a. If the pressure is great enough, the lower end of the arm 12 carrying the contact will move to the left until the contact 15 closes against the contact 14, thereby closing an electric switch. As stated above, this switch can be seen in FIG. 3 and the function 1 thereof will be described hereinafter. Movements of the arm 12 beyond mere contact closure causes rotation of the arm lle against the bias of the spring 16.

Referring again to FIG. 1, this figure illustrates a governor generally designated by the reference numeral 20 and illustrated in detail in FIGS. 4 and 5. The governor comprises a metal frame 21 having a pair of bearings 22 located on one end and supporting a shaft 23 on which a rubber-tired wheel 24 is keyed. The rubbertired wheel 24 rotates on the flange 5a of the drum 5 so that when the drum 5 rotates, the wheel 24 and the shaft 23 to which it is keyed will also be driven by the motion of the drum flange 5a. This rotation is transmitted through bevel gears 25 which transfer the rotation from the shaft 23 to a shaft 26 connected with a gear box 27 containing a shaft speed increaser which delivers rotation to a shaft 28 at a higher rate of rotation than the input shaft 26. The right end of the shaft 28 is journaled in a U-shaped auxiliary frame 29 which is mounted on the frame 21. A governor sleeve 30 is carried on the shaft 28 and has an enlarged boss 30a at its left end. Another sleeve 31 is mounted on the shaft 28 and pinned thereto for unitary rotation therewith. This sleeve 31 has a flange 31a having two pairs of lugs 31b through which pins are passed for the purpose of supporting fly weight arms 32. When the shaft 28 is rotated, the sleeve 31 rotates therewith and causes similar rotation of the flange 3101. Because of the step-up gearing in the gear box 27, the shaft 28 rotates rather rapidly for relatively slower rotations of the shaft 23 and therefore the fiy weights 32 tend to be thrown radially outwardly by centrifugal force. As they are thrown outwardly, the small arms 32a at the inner ends of the fly weight arms move to the right and press against the boss 30a of the sleeve 30 and move it rightwardly against the action of a spring 33 which is supported at its right end by a screw 33:: in a rod 34 which is attached to the sleeve 30. The rod 34 has a lower extension 34a which is captivated between two stops 35 which serve to prevent rotation of the sleeve 30 without limiting the rightward motion thereof. The left end of the spring 33 is mounted on a small rod 36 supported at the left end of a lead screw 37 threadedly supported in bosses 38 comprising a part of the auxiliary frame 29. The lead screw 37 can therefore be adjusted in and out to valy the tension of the spring 33, and thereby provides means for adjusting the speed at which the governor is actuated. A knurled knob 37a is provided on the governor lead screw 37 for convenience in turning the latter.

A push rod 40 extends through a bore in the auxiliary frame 29 and engages a set of breaker points including a stationary point 41 and a movable point 42 connected respectively with wires 41a and 42a which wires and contacts can also be seen in FIG. 3. The movable contact 42 is supported on an arm 43 and the push rod 40 bears directly against the arm 43 so that when the sleeve 30 is moved to the right by the centrifugal outward mo tion of the fly weights 32, the contacts will be opened. Normally, a leaf spring 44 maintains the contacts 41 and 42 closed. In other words, when the rubber-tired wheel 24 is motionless the contacts are closed, but when the rotation rate of the wheel 24 exceeds a predetermined value as set by adjustment of the lead screw 37, the contacts are then opened to provide the operation which will be hereinafter more fully explained.

This entire governor assembly 20 is supported on a channel 45 which is welded to the frame 8 of the draw works. A small lever 46 which can be seen best in FIGS. 2 and 4 is attached to the under side of the frame 21 which is supported on a hinge 47 having one leaf Welded to the under side of the frame 21 and having its other leaf welded to the channel 45 which is secured to the frame 8 of the hoist, the governor 20 in FIG. 5 being shown in the same position as it is shown in FIG. 1. When the lever 46 is in the up position as shown in FIG. 2, the governor assembly 20 is in operative position shown in FIG. 2 in which the rubber-tired wheel 24 engages the surface of the drawwork flange 511 so as to be driven thereby. On the other hand, the lever 46 can be pivoted through 90 degrees in the clockwise direction rom its position as shown in FIG. 'Q. In this 90 position the wheel 24 will no longer contact the flange 5a and therefore the governor will not operate, the entire frame 21 having been rotated 90 degrees around the hinge 47 in this position so that the wheel 24 is out of contact with the drum flange 5a.

A chain 47 visible in FIGS. 1 and 2 is connected with the lever 46 by a coil spring 48. When the chain 47 as shown in FIG. 2 has its left end wedged in a fitting 49, the spring 48 will be tensioned, and the governor will be maintained in the position illustrated in FIG. 2, which is also the same position of the hinge as illustrated in FIG. 5 wherein the rubber-tired wheel is driven by the flange 5a.

Referring again to FIG. 1, the draw-works includes a jack shaft 50 which is rotated continuously by a prime mover P, and this jack shaft 50 drives through a sprocket chain 51 the shaft 52 of an electric clutch, the structure of which is not novel per se. This clutch can be purchased on the open market and in the working embodiment of the present invention comprises a 12-volt D.C. magnetic clutch including clutch control means comprising a winding associated with the other parts of the clutch so that the latter are disengaged when the current is removed from its windings. The clutch, generally referred to by the reference numeral 53, has an output shaft 54 in which a small drum 55 is keyed. The input shaft 52 of this clutch is continuously driven as stated above, but the output shaft of the clutch and the drum 55 located thereon are driven only when electric current is passed through the winding 56 of the clutch illustrated schematically in FIG. 3. A length of sash cord 57 has several turns wrapped around the drum 5S and the right end of the sash cord is shown in FIG. 1 as connected with the brake-release arm 7 whereas the left end of the sash cord 57 is connected through a tension spring 53 with a fixed point 59 on the frame of the hoist. The length of sash cord and the tension of the spring is selected in such a way that when the brake-release lever 7 of the hoist is in the lowermost position at which the brake is fully applied, enough tension is put on the sash cord 57 by the spring 58 that the cord will be tightened on the drum 55 so that if the drum 55 rotates, the right end of the sash cord will raise the lever 7 sufiiciently to release the brake shoe 6 on the cable drum 5. However, having raised the arm 7, the sash cord 57 will be slackened on the left side, and therefore the turns of the sash cord around the drum 55 will no longer be tight enough to cause tight engagement of the drum 55 by the sash cord 57. In other words, the sash cord will be loosened and released on the drum 55 and therefore the brake-release arm '7 will be allowed to fall down again and reapply the brake 6 against the drum 5. This structure, thus, provides actuator means having an intermittent action whereby the brake-released lever 7 is operated intermittently for brief intervals of time whenever the magnetic clutch 53 is engaged by passage of current through the winding 56.

Referring now to the schematic diagram of FIG. 3, this figure illustrates a source of direct current in the form of a battery 6%, which battery is of the proper voltage to energize the winding 56 of the magnetic clutch 53. The current from the battery is controlled by a switch 61, and passes through the contacts 14, 15, 41 and 42 in order to energize the clutch winding 56. The contacts 41 and 42 which are associated with the speed governor 2% are normally closed, and the contacts 14 and 15 associated with the Bourdon gauge are normally open, but are closed when the tension on the hoist line 1 as measured by the transmitting unit 10 exceeds a predetermined value.

When the control system of the present invention is to be placed in operation, the switch 61 is closed and the governor 24 is swung into position and held in place by the chain 47 and the tension of the spring 48 on the arm as as shown in FIG. 2. A weight W is installed in place on the brake arm, this weight being sufficient to normally prevent rotation of the drum 5 to pay out the hoist line 1, and the sash cord is passed around the small drum 55 on the magnetic clutch 53, as described above. The contact 1 2- is adjusted with respect to the position of the contact for a desired weight on the bit at which weight the contacts will just be closed. The drilling is then begun to cause the bit to penetrate into the strata, the weight on the bit decreasing as the bit penetrates because this weight is transferred to an increasing extent to the hoist line 1. Therefore, the tension in the hoist line 1 increases as measured by the transmitting unit 10 and as this tension increases the arm 12 rotates around the pivot 12a in the gauge assembly 11 shown in FIG. 6, with the result that the contact 15 approaches the adjustable contact 14. When the contacts meet, the electrical circuit shown in FIG. 3 is closed and current is passed through the winding 56 of the electric clutch 53. Thus, the clutch becomes energized and begins to rotate the drum 55 counterclockwise as shown in FIG. 1 so that the sash cord 57 is pulled to the left to release the brake 6 by raising the brake-release arm '7. The clutch 53 remains energized until the contacts 14 and 15 are again opened but the tension on the sash cord 57 is only applied intermittently so as to release the brake 6 by a series of jerks each one of which is interrupted when slack appears in the left portion of the hoist line, FIG. 1, thereby releasing the grip of the sash cord 57 on the rotating drum 55. When the brake has been intermittently released a sufiicient number of times to permit more hoist line 1e to pass from the drum 5 and thereby lower the bit in the bore hole, the tension of the dead end 1a of the hoist line will be decreased so that the Bourdon gauge will relax and permit the arm 12 to rotate clockwise and remove the contact 15 from the contact 14 and thereby break the circuit of FIG. 3 to dc-energize the winding 56 of the clutch 53. in actual operation, the governor contacts are set to open with relatively slow rotation of the drum 5, whereby the engagement of the clutch 53 is made intermittent, but is rapid enough so that the adjustment appears to be almost continuous as the governor starts and stops. This motion minimizes the likelihood of sticking of the bit if it suddenly penetrates a cavern of rather soft formation because the bit is not permitted to drop sufficiently rapidly that it could take an excessively large bite and become stuck in solid strata below the cavern just penetrated. Also, the governor prevents rapid descent of the bit and thereby prevents damage to the drilling string which might occur if the bit dropped suddenly onto a sol-id strata through a considerable distance.

I do not limit my invention to the exact form shown in the drawing, for obviously changes can be made therein within the scope of the following claims.

I claim:

1. An automatic system for controlling the division of the weight of a drilling string between the weight on the bit at the lower end of the string and the weight on a supporting hoisting line by paying out the line from a drum having a brake and brake-release means, comprising a first switch; weight-sensitive means connected with the hoisting line and including means for setting a predetermined standard of weight, means for measuring the weight on said hoisting line and means for closing said first switch when the weight measured exceeds said predetermined standard; a second switch; speed-governor means coupled with said drum and having means for opening said second switch when the rotation rate of said drum exceeds a preselected rate; and actuator means including an electrical control circuit coupled with said switches for energizing said actuator means when both switches are closed, said actuator means being coupled to said brake-release means to release the brake when energized.

2. In a system as set forth in claim 1, said speed governor means being pivotally mounted on a fixed support adjacent said drum and having a governor-drive wheel adapted to contact said drum when the governor is in operative position thereagainst; and releasable means for maintaining said governor in said operative position.

3. :In a system as set forth in claim 2, said governor means having speed-sensitive adjustment means whereby the rate at which said second switch is opened by the governor means can be preselected.

4. In a system as set forth in claim 1, said actuator means comprising periodic intermittent-motion means alternately actuating and releasing said brake-release means during the entire time both of said switches are closed.

5. In a system as set. forth in claim 4, said intermittent-motion means comprising a shaft; prime-mover means to rotate said shaft when both switches are closed; cord means having a turn about said shaft and connected at one end to said brake-release means to actuate the latter when pulled by the shaft; and tension spring means connecting the other end of said cord means to a fixed point, the tension on the cord means being removed each time the end of the cord means attached to the brakerelease means is pulled.

6. In a system as set forth in claim 5, magnetic clutch means having a control winding and coupling said shaft to said prime-mover means; and a source of power connected with said Winding through said two switches.

7. In a system as set forth in claim 4, said governor 3 means having speedsensitive adjustment means whereby the drum rotation rate at which said second switch is opened by the governor means can be preselected; and said weight sensitive means having adjustment means whereby the weight value at which said first switch is closed can be predetermined.

8. An automatic system for controlling the division of the weight of a drilling string between the weight on the bit at the lower end of the string and the weight on a supporting hoisting line by paying out the line from a drum having a brake and brake-release means, comprising weight measuring means for measuring at least one of said weights; clutch means having two shafts; primemover means for continuously rotating one of said clutch shafts; clutch control means coupled to said weight measuring means for energizing said clutch when a certain predetermined value of weight is measured; and intermittent-motion coupling means connected between the other clutch shaft and said brake release means, whereby the brake is alternately applied and released during the entire time said clutch means is actuated.

9. In a system as set forth in claim 8, said intermittent-motion coupling means comprising cord means having a turn about said other clutch shaft and connected at one end to said brake-release means to actuate the latter when pulled by the shaft; and tension spring means connecting the other end of said cord means to a fixed point, the tension on the cord means being removed each time the end of the cord means attached to the brake-release means is pulled.

10. In a system as set forth in claim 8, said weight measuring means including an electric switch operated when said measured weight reaches said predetermined value; said clutch control means comprising an electrically energized Winding; and a power source coupled through said switch to said winding.

11. An automatic system for controlling the divison of the weight of a drilling string between the weight on the bit at the lower end of the string and the weight on a supporting hoisting line by paying out the line from a drum having a brake and brake-release means, comprising weight measuring means for measuring at least one of said weights; periodic intermittent-motion means coupled to said brake-release means to alternately apply and release said brake during the entire time said intermittentmotion means is actuated; and actuator means coupled with and controlled by said measuring means for actuating said intermittent-motion means during the entire time the weight on the bit is below a predetermined value.

12. In a system as set forth in claim 11, said intermittent-motion means comprising a shaft; prime-mover means to rotate said shaft when both switches are closed; cord means having a turn about said shaft and connected at one end to said brake-release means to actuate the latter when pulled by the shaft; and tension spring means connecting the other end of said cord means to a fixed point, the tension on the cord means being removed each time the end of the cord means attached to the brake-release means is pulled.

13. In a system as set forth in claim 12, said actuator means comprising an electric switch operated by weight measuring means when said measured weight reaches said predetermined value, magnetic clutch means having a control winding and coupling said shaft to said prime mover; and a source of power connected with said winding through said switch.

14. In a system as set forth in claim 11, governor means for limiting the rate of rotation of said drum to a preselected maximum.

References Cited in the file of this patent UNITED STATES PATENTS Hartford July 15, 1924 Abraham Aug. 23, 1960 THER REFERENCES 

